An essential process in brewing is the brewing house process for producing wort. The wort produced by the lauter tub must be boiled, wherein bitter and aromatic components of the hops are transferred into the wort and at the same time proteins as well as undesired volatile components, such as DMS (dimethylsulfide) can be eliminated or evaporated.
The boiling of wort is carried out in a wort copper. Basically, wort coppers with internal boilers and wort coppers with external boilers exist. In the case of wort coppers with internal boilers, the boiler is located in the wort copper. The internal boiler is for instance a tubular heat exchanger located in the wort copper, with the wort rising through its perpendicularly arranged tubes.
In the case of wort coppers with external boilers, the wort is heated by an external boiler arranged outside of the copper. The wort is permanently drawn off from the lower portion of the wort copper and is for instance pumped by means of a pump through the external boiler and is re-supplied to the wort. During return into the copper the wort expands. This leads to a desired strong evaporation. Usually, tubular heat exchangers or plate heat exchangers are used as external boilers. Contrary to internal boilers, external boilers reveal a number of advantages. The wort outlet temperature and circulation quantity can be controlled precisely. The heating surface required and the dimensioning of the external boiler is freely selectable and not restricted by the size of the copper. The size of the wort copper can therefore be reduced.
The wort copper with an external boiler still involves the disadvantage that the wort stock in the wort copper does not circulate sufficiently. Although the circulating pump is dimensioned such that the copper content can be circulated approximately eight times per hour, however, it is not ensured thereby that each wort particle runs eight times through the boiler. A sufficient circulation is particularly not guaranteed in the lower portions and corner portions of the wort copper.
Problems particularly during phase boiling result, which is the prerequisite for an energy-saving wort boiling. During phase boiling the efficiency of the circulating pump and/or the heating power of the boiler during the heating and boiling process is for instance controlled and adapted to a target value curve, as for instance explained in EP 0875559 B1. The boiling process is carried out in various phases, wherein the heating power of the wort boiler depends on a difference between the target and actual value. Particularly in the phases in which the heating power is low or it is not heated at all, the problem occurs that the copper content is not sufficiently circulated, since caused by the lowered heating power the relief energy of the heated wort is not sufficient to provide a good circulation.
On the whole, a high pump efficiency is required in the known wort coppers and wort boiling methods, which leads to a throughput speed of approx 2 to 3 m/sec in the external boiler tubes, since otherwise crustification occurs.
It was also already proposed, as shown in FIG. 7, that the wort heated by an external boiler is supplied through an infeed tube which projects into a rising pipe. However, it was also proven in this system that a sufficient circulation of the wort does particularly not occur in phase boiling.